package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;

/**
 * @author 梦龙
 * @date 2024/1/22 17:05
 */

public class SimpleRedisLock implements ILock {

    private StringRedisTemplate stringRedisTemplate;
    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    private String name;

    public SimpleRedisLock(StringRedisTemplate stringRedisTemplate, String name) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }

    // 尝试获取锁，因为不一定获取得到
    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程标示
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        // 获取锁
        // setIfAbsent 表示如果不存在
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
        // 如果直接返回success,有个自动拆箱的过程,success有可能是null导致空指针异常
        // return success;
        // 所以用下面的来比对,如果是null或者false就返回false
        return Boolean.TRUE.equals(success);
    }

    // 释放锁
    @Override
    public void unlock() {
        // 调用lua脚本
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + name),
                ID_PREFIX + Thread.currentThread().getId());
    }
//    @Override
//    public void unlock() {
//        // 获取线程标示
//        String threadId = ID_PREFIX + Thread.currentThread().getId();
//        // 获取锁中的标示
//        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
//        if (threadId.equals(id)){
//            // 比较
//            stringRedisTemplate.delete(KEY_PREFIX + name);
//        }
//    }
}
